fix: start gate before registry in supervision tree

The registry init calls nova_resilience_gate:deps_provisioned()
(a gen_server cast), but the gate process hadn't started yet since
it was second in the child list. The cast was silently dropped,
leaving the system permanently not-ready.

Swapping the order ensures the gate is alive when the registry
sends the deps_provisioned notification.

Author: Taure

src/nova_resilience_sup.erl

@@ -6,8 +6,8 @@ Top-level supervisor for nova_resilience.
 Supervision tree:
 ```
 nova_resilience_sup (one_for_one)
-  ├── nova_resilience_registry (gen_server)
-  └── nova_resilience_gate (gen_server)
+  ├── nova_resilience_gate (gen_server)
+  └── nova_resilience_registry (gen_server)
 ```
 """.
 
@@ -22,14 +22,14 @@ start_link() ->
 init([]) ->
     Children = [
         #{
-            id => nova_resilience_registry,
-            start => {nova_resilience_registry, start_link, []},
+            id => nova_resilience_gate,
+            start => {nova_resilience_gate, start_link, []},
             shutdown => 5000,
             type => worker
         },
         #{
-            id => nova_resilience_gate,
-            start => {nova_resilience_gate, start_link, []},
+            id => nova_resilience_registry,
+            start => {nova_resilience_registry, start_link, []},
             shutdown => 5000,
             type => worker
         }